1.. Field of the Invention
The present invention relates to a radiation image capturing system, a radiation detecting apparatus, an image capturing base, a radiation image capturing method, and a program for correcting the magnifications of radiation images captured by a plurality of image capturing apparatus of different specifications.
2.. Description of the Related Art
In the medical field, there have widely been used radiation image capturing apparatus which apply a radiation to a subject and guide the radiation that has passed through the subject to a radiation detector, which captures a radiation image from the radiation.
One known radiation detector is a stimulable phosphor panel which stores a radiation energy representative of a radiation image in a phosphor. When the stimulable phosphor panel is irradiated with stimulating light, the phosphor emits stimulated light representative of the stored radiation image. The stimulable phosphor panel with the radiation image recorded therein is supplied to a reading apparatus which reads the stored radiation image as a visible radiation image.
In sites of medical practice such as operating rooms or the like, it is necessary to read recorded radiation image information immediately from a radiation detector for the purpose of quickly and appropriately treating the patient. As a radiation detector which meets such a requirement, there has been developed a radiation detector having a solid-state detector for converting a radiation directly into an electric signal or converting a radiation into visible light with a scintillator and then converting the visible light into an electric signal to read a detected radiation image.
There are available in the art various image capturing apparatus of different specifications for capturing radiation images using radiation detectors depending on the conditions of patients as subjects to be imaged and image capturing conditions including body regions to be imaged. Those different image capturing apparatus are controlled by respective processors having specifications corresponding to the specifications of the image capturing apparatus. According to a known radiographic system, various image capturing apparatus and processors are connected to a radiology information system (RIS) by an in-house network, and patient information and image capturing conditions set by the RIS which include image capturing methods, body regions to be imaged, radiation dose, etc. are supplied to the processors, which then control the corresponding image capturing apparatus to capture radiation images (see Japanese Laid-Open Patent Publication No. 2006-247137).
If a body region of interest of one patient is to be periodically imaged for follow-up observations, then it is necessary to capture radiation images of the body region with the same image capturing apparatus under the same image capturing conditions. However, the same image capturing apparatus may not be available when the patient has suffered certain status changes or when the image capturing apparatus is occupied. For example, when a patient is unable to walk, it is imaged by an image capturing apparatus while lying on the bed, and when the same patient is able to walk at a later time, it is imaged by another image capturing apparatus while in an upstanding posture. In this case, the radiation images of the patient are captured by the different image capturing apparatus. If the patient is spaced from the radiation detectors of the different image capturing apparatus by different distances or the radiation images captured by the different image capturing apparatus are processed by different image processing methods, then the radiation images may have different magnifications and hence may not be accurately compared with each other.
Various technologies have been used to process a radiation image of a subject, in relation to the subject according to the related art. Those technologies include an apparatus for processing a radiation image of a subject captured by an image capturing apparatus such that the generated radiation image has the same size as the subject (see Japanese Laid-Open Patent Publication No. 07-265286) and an apparatus for simultaneously capturing radiation images of a subject and a reference member of known dimensions and determining the dimensions and area of the subject from the radiation image of the reference member (see Japanese Laid-Open Patent Publication No. 2004-144651). Another known apparatus has an ordinary X-ray source for capturing ordinary radiation images and a microfocal X-ray source for capturing enlarged radiation images, which can selectively be used depending on a body region of interest of a subject for changing image magnifications (see Japanese Laid-Open Patent Publication No. 2005-270201).
The apparatus disclosed in Japanese Laid-Open Patent Publication No. 07-265286) displays the radiation image of the subject in full scale, but does not equalize the scales of radiation images captured by different image capturing apparatus. Though the apparatus disclosed in Japanese Laid-Open Patent Publication No. 2004-144651. can determine the dimensions of the subject, it does not equalize the scales of radiation images, either. The apparatus disclosed in Japanese Laid-Open Patent Publication No. 2005-270201. does not equalize the scales of radiation images captured by different image capturing apparatus as it only captures and displays radiation images at different magnifications depending on body regions of interest to be imaged.